Surface apparatus for handling an elastic column

ABSTRACT

This apparatus is provided with at least two devices for gripping an elastic column, including a lower and an upper gripping device, one at least of these devices being displaceable along the axis of the column in a released position. In this apparatus each of said devices is constituted by a plurality of separate gripping elements arranged in series, these gripping elements being interconnected through elastic means.

United States Patent 1 1 Reynard et al.

[111 3,711,000 1 Jan. 16, 1973 [54] SURFACE APPARATUS FOR HANDLING ANELASTIC COLUMN [75] Inventors: Remi Reynard, Montessori; Roger Tindy,Bougival; Edmond Daniel, Saulx-Les-Chartreux, all of France [73]Assignee: Institut Francais du Petrole des Carburants et Lubrifiants,Paris, France 22 Filed: Sept. 9, 1971 211 App]. No.: 178,924

Related US. Application Data [63] Continuation-in-part of Ser. No.854,983, Sept. 3,

[30] Foreign Application Priority Data Sept. 4, 1968 France ..68l65l09[52] US. Cl. ..226/8, 226/112, 226/115, 226/162 [51] Int. Cl. .J ..B65h17/36 [58] Field of Search ..226/8, 158, 162, 163, 164,

[56] References Cited UNITED STATES PATENTS 1,028,523 6/1912 Anderson..226/l64 X 3,330,459 7/1967 Cullen ..226/l73 Primary ExaminerRichard A.Schacher Attorney-Craig, Antonelli & Hill ABSTRACT This apparatus isprovided with at least two devices for gripping an elastic column,including a lower and an upper gripping device, one at least of thesedevices being displaceable along the axis of the column in a releasedposition.

ln this apparatus each of said devices is constituted by a plurality ofseparate gripping elements arranged in series, these gripping elementsbeing interconnected through elastic means.

11 Claims, 7 Drawing Figures PATENTEUJM 16 I975 3.711.000

sum 1 or 4 INVENTORS ROGER TINDY REMI REYNARDI wma game/v0 DA I LPATENTEDJAN 16 Ian SHEET 2 [IF 4 I INVENTORS REM! REYNARD ROGER TINDYEDMOND DANIEL ATTORNEYS PATENTEDJAH 16 I973 SHEET 3 BF 4 INVENTORS REMIREYNARD ROGER TINDY EDMOND DANIEL BY r (JUN?) ATTORNEYS PATENil-ID AN 1m 3.71 1. 000 SHEET u 0F 4 I INVENTORS REMI REYNARD ROGER TINDY EDMDNDDANIEL BY 01%, RANQQ; r M110 ATTORNEYS SURFACE APPARATUS FOR HANDLING ANELASTIC COLUMN This is a continuation-in-part application of copendingUS. patent application Ser. No. 854,983, filed on Sept. 3, 1969.

The present invention relates to a surface apparatus enabling an elasticcolumn, particularly a column introduced into a borehole in the ground,to be handled, i.e., lowered into the borehole and raised back to theground surface.

This column may, for example, be a flexible drill pipe used in thedrilling process wherein there is substituted for the usual string ofrigid stems a continuous flexible pipe at the lower end of which abottom motor ,is directly connected to a drill bit for actuationthereof.

It is however also possible to use the apparatus according to theinvention for handling a column or any elongated member of solidcross-section lowered in a borehole, such as a cable, liable to undergosome elongation under its working conditions.

The handling apparatus according to the invention is of a type providedwith devices for gripping the elastic column, some of these grippingdevices being movable along the column.

A first object of the invention is to provide an apparatus which may beassociated with conventional equipment used in conventional drillingmethods, such as derricks, hoisting devices using winches, cables andpulley blocks, without requiring any substantial change in theseequipments.

The main object of the invention is to provide an apparatus for handlingan elastic column capable of supporting loads which may reach manyhundred tons, without imparting any sliding to this column relative tothe gripping devices, under the action of the load, which slidingresults in deteriorations of the wall of the column which are in contactwith these gripping devices, or to creeping phenomena of this column,relative to the gripping devices applied thereto.

The apparatus according to the invention, whereby are achieved theseobjects, includes at least two devices for gripping the elastic column,comprising a lower and an upper gripping device, each of said devicesbeing associated with means for displacing at least one of said devicesparallelly to the column axis, means for sequentially controlling saiddisplacing means and for causing a gripping action on said columnthrough either of said gripping devices, so that there is always atleast one of said gripping devices in its gripping position, thedisplacement of said gripping devices being effected in a firstdirection in the gripping position of the device and in the oppositedirection in the released position of this device.

According to the invention, each of said devices for gripping the columnis constituted by a plurality of separate gripping elements surroundingthe column, arranged in series and interconnected through elastic means.

According to one particular embodiment of the invention, the elasticconnection between the gripping elements of a gripping device isconstituted of plates of elastic material, each gripping element beingprovided with a tubular housing engaged in a sleeve member integral withthe tubular housing of an adjacent gripping element, thereby forming atelescopic mounting and the plates of elastic material being securedboth to the external wall of each tubular housing and to the internalwall of the sleeve member wherein this housing is inserted.

The suspension of each gripping element from the adjacent upper grippingelement might also be achieved by any other elastic means, using forexample spring means or jack means connected to a source of fluid underpressure.

The so-constituted telescopic mounting exhibits the essential advantageof enabling the gripping jaws equipping each gripping element to followa substantial elongation of the elastic column within the lower and theupper gripping devices.

An embodiment of the invention will be described hereinunder, withreference to the attached drawings, wherein FIG. 1 diagrammaticallyillustrates an overall view of the device;

, FIG. 2 illustrates a gripping element;

FIGS. 3, 3A, 3B and 3C represent schematically particular embodimentsfor the arrangement of the gripping elements each consisting of lowerand'upper gripping members;

FIG. 4 illustrates an embodiment of the means for synchronouslycontrolling the hoisting winch of the upper gripping device and forcontrolling reversible jacks adapted to move the jaws into and out ofgripping position.

In FIG. 1 which diagrammatically shows an overall view of a drillingequipment for a flexible drill pipe, including an apparatus according tothe invention for handling this pipe, the reference numeral 1 designatesthe drill pipe and 2 a derrick at the top of which the pipe passes overa pulley 3.

The pipe 1 is stored on a winch 4 associated with means for supplyingthe pipe with drilling fluid through a rotary coupling and passesbetween this winch and pulley 3 through a tension regulating devicediagrammatically represented at 5, the winch 5 and the tensionregulating device 5 forming however no part of the present invention.

The apparatus according to the invention, used for handling the flexiblepipe 1, comprises a lower device 6 for gripping this pipe, this lowergripping device consisting of a series of gripping elements surroundingthe flexible pipe, each of which is provided with gripping jaws and witha device for moving these jaws into and out of gripping position,adapted to reversibly displace them between a gripping position of thepipe 1 and a released position wherein the pipe can freely slide betweenthe jaws and giving passage to the rigid metallic elements connected tothe lower part of the flexible pipe, these elements comprising the drillbit and the driving motor for this bit.

This lower gripping device 6 is stationary, being integral with thesubstructure 7 of the derrick.

In combination with this stationary lower gripping device, the apparatusaccording to the invention includes an upper device 8 for the pipe 1,this device also consisting of a series of gripping elements, each ofwhich is provided with jaws associated with a reversible device fordisplacing these jaws in a direction transverse to the pipe. This upperdevice is movable vertically over a stroke L along the pipe, in thereleased position of its jaws.

In the embodiment illustrated by FIG. 1, the means providing for thedisplacement of the upper gripping device 8 along the pipe 1 isconstituted by a hoisting device of the type used in the rotary drillingmethod for handling the drill string and its elements.

This device includes cables 9 passing over a stationary pulley block 10located at the top of the derrick (this stationary pulley block includesforexample two pulleys located on both sides of pulley 3) and over atravelling block 11 from which is suspended the upper gripping device 8,by means of a hook 12. The vertical displacements of the travellingblock 11 are achieved by means of a winch 13 on which is wound a freeend 9a of cables 9;

The adaptation of this conventional hoisting device to the embodimentillustrated by FIG. 1 of the apparatus according to the invention, forhandling a flexible pipe, is achieved by providing an axial passage suchas 14 through the travelling block 11 and axial bores through the hook12, this passage and these bores being of a sufficient diameter forproviding a free passage to the flexible drill pipe.

In combination with the above-indicated elements, the device accordingto the invention includes means for synchronously controlling on the onehand the means for displacing the upper gripping device 8 (winch 13 inthe illustrated embodiment) and'on the other hand the means for movingthe jaws of the two gripping devices 6 and 8 into and out of grippingposition.

These control means, which are not shown on FIG. 1 will be describedhereinunder, with reference to FIG. 4.

These means are adapted to repeatably provide for either of the twofollowing series of operations:

I. RAISING OF THE PIPE l. Simultaneous gripping of the pipe by the jawsof the. two gripping devices 6 and 8, when the upper gripping device isin its lower position, substantially in contact with the device 6.

2. Releasing of the jaws of the lower gripping device 6, the uppergripping device remaining in its gripping position.

3.'Actuating the hoisting winch 13 so as to raise the upper grippingdevice 6.

4. Stopping this upper gripping device in its uppermost position at theend of its stroke L.

5. Moving the jaws of the lower gripping device into gripping position,then releasing the jaws of the upper gripping device 8, while the jawsof the device 6 remain in their gripping position.

6. Lowering of the empty device 8 over the stroke L, back to itslowermost position and stopping it in this position.

7. Moving the jaws of the device 8 into gripping position, in the lowerposition of this gripping device.

II. LOWERING OF THE PIPE l. Simultaneous gripping of the pipe by thejaws of the two devices 6 and 8, while the upper gripping device is inits upper position at the top of the derrick.

2. Releasing of the jaws of the lower gripping device 6, the uppergripping device'8 remaining in its gripping position.

3. Downwardly moving the device 8 under the load of the flexible pipewith braking of this movement, for example through winch 13.

4. Stopping of the device 8 in its lowermost position.

5. Moving the jaws of the device 6 into gripping position, thenreleasing the jaws of the device 8, while the jaws of the device 6remain in their gripping position.

6. Raising back the device 8 without load up to its uppermost positionand stopping it in this position.

7. Moving the jaws of the device 8 into gripping position, in the upperposition of this device.

FIG. 2 diagrammatically illustrates the structure of an element orgripping element constituting each of the gripping devices 6 and 8.

This element includes at least two gripping jaws for the pipe 1 (jaws 15and 16) which may grip the pipe 1 by means of reversible hydraulic jacks17a, 17b which bear against a tubular-housing 18 whereon these jacks arearticulated.

The jaws 15 and 16 roll on rollers along inclined guide paths integralwith this tubular housing.

These jaws and their guide paths constitute an automatic gripping systemso designed as to exert on the pipe a gripping action alwaysproportional to the downwardly directed vertical force (indicated by thearrow in FIG. 2) to which it is subjected as a result of frictionbetween the jaws and the pipe, this arrangement being a safety factor.

In the examplative embodiment of FIG. 2, each of the jaws 15 and 16 isconstituted by two superimposed wedges integral with each other.

The reference numerals 37, 38, 39 and 40 designate rollers the axes ofwhich are carried by jaws 15 and 16, these rollers rolling alonginclined guide paths carried by the tubular housing 18.

Each gripping element may obviously be provided with more than twogripping jaws, distributed along the periphery of the flexible pipe 1.

Inside each gripping element, such as the one shown by FIG. 2, therelative elongation. of the pipe 1 withrespect to the gripping jaws willbe reduced since each gripping element only supports a fraction of theoverall load supported by each of the gripping devices 6 and 8 andbecause moreover the length of the pipe 1 passing through this elementis only a fraction of the overall length of the pipe 1 passing througheach of the gripping devices 6 and 8.

In order to permit some relative displacement without any creeping ofthe pipe 1 inside each gripping jaw, it will be advantageous to provideeach gripping I jaw, such as jaw 15 or jaw 16, with an internal coatingor shoe made. of an elastomer on the internal wall of this jaw whichcomes into contact with pipe 1, or to fix the shoe to a pad made of anelastic material, such as an elastomer.

This shoe may moreover be divided into several super-imposed elements,optionally with some clearance left between the elements constitutingthe shoe.

FIG. 3 diagrammatically shoes a telescopic arrange-v ment, according tothe invention, of the gripping ele-' ments constituting each of thegripping devices 6 and 8.

In the illustrated embodiment the elements mounted in series are four innumber, but this number is by no way limitative.

The number n of gripping elements constituting each gripping device willbe selected sutficiently high so that, taking into account thecoefficient of elongation of the column or pipe and the maximum load Tto be supported by the lower and upper gripping devices, the maximumload T/n to be supported by each gripping element will correspond to atolerable elongation ofthe portion of column or pipe passing throughthis gripping element.

The tubular housings of three of the four gripping elements (housings18a, 18b and 180) is at one of its ends, for example at its lower end,extended through a sleeve member (sleeve members 19a, 19b, 190) which isintegral with this tubing and is adapted to receive the housing of anadjacent gripping element, thereby constituting a telescopic mounting inwhich the tubular housing 18 of an element and the sleeve member 19surrounding this housing are interconnected through an elasticconnection, for example by inserting one or more plates of elastomer,particularly an annular coating or sleeve of elastomer (coatings 20a,20b and 200).

The fixation of the plates of elastomer onto the external wall of thehousing 18 and to the internal wall of the sleeve member 19 may forexample by achieved by vulcanization.

When the assembly of the gripping elements shown in FIG. 3 constitutesthe movable upper element (FIG. 1), the housing 18a of the upper beltwill be suspended from the hook 132.

FIG. 3A represents schematically another embodiment of the arrangementof the elements 18 to 18d constituting one gripping member.

Each gripping element is rendered integral with two crowns, a lowercrown 100 and upper crown 101, the

end elements being equipped with only a single crown. These crowns havebeen identified with the reference numerals 101a, 101b, and 1010, and100b, 1001: and 100d in FIG. 3A. Each upper crown carries a plurality ofrods (102b, 1026 and 102d) being adapted to glide through orifices(103a, 103b and 1030) provided in the lower crown corresponding to theadjacent element positioned directly above.

An elastic spring (104b, 1040 and 104d) operating at the compression isplaced between the lower crown of an element in a stopping plate madeintegral with the rods (102b, 1020 and 102d). The springs thus allow,because of the action of the charge supported by the column, for arelative displacement of the consecutive gripping elements constitutingthe gripping member.

FIG. 3B is a modified embodiment as to compare to FIG. 3A in which thesprings have been replaced by jacks (105a, 105b, 1050), for example,pneumatic jacks connected by means of ducts (106a, 106b and 106a) to astorage or reservoir (not shown) containing a gas whose pressure makesit possible to regulate the stiffness of the elastic means thusprovided.

FIG. 3C is another embodiment regarding these elastic means. In thisexample, the castings and jackets of the successive elements glidewithin each other, delimiting volumes supplied with gas under pressureby means of ducts (106a, 106b and 1066).

An embodiment of the means for synchronously controlling the hoistingwinch 13 and the jacks which provides for moving the jaws into and outof gripping position is described hereinunder with reference to FIG. 4.

The reversible jacks 21a to 28a controlling the jaws 21b to 28b of theupper gripping device 8 and the jacks 29a to 36a of the jaws 29b to 3612of the lower gripping device 6 are supplied with hydraulic-fluid from atank 45, by means of a motonpump unit W, through two slide-valves 46 and47 which are mechanically interconnected, so as to be displacedsynchronously.

This connection is diagrammatically indicated by a rod 48 in FIG. 4.

An arm 49 providing for electrical contact and forming a T with theconnecting rod 48 integral with this arm provides for synchronouscontrol of the actuation of the winch 13 and of that of the jaws, byclosing electrical contacts A, O and B connected respectively toelements 59, 60 and 61 adapted to achieve the control of the motordriving the winch 13 in the direction corresponding to the operation tobe affected on the column. These elements may comprise, for example,reversing means of the mechanical type with two positions in such amanner that for the operation of raising the pipe, the contact A assuresthe engagement of the winch in the direction for raising the movableupper gripping member, and the contact B assures the disconnection ofthe which 13, allowing for lowering the member 8 due to the effect ofthe charge with braking of the winch;

for operation of lowering the pipe, the contact A assures thedisconnection of the winch 13, allowing for the lowering of the member 8due to the effect of the charge with braking of the winch, then thecontact B assures the engagement of the winch in the direction ofraising the upper movable gripping member, the contact O assuring ineach of these operations the stopping of the which.

The movements of the assembly of the slide-valves 46 and 47 arecontrolled through an electrovalve 50, which, by admission of hydraulicfluid onto either of the end faces 51 and 52 of this assembly ofslide-valves, through the ducts shown in dotted lines in FIG. 4, causesthe displacement of this assembly of slide-valves either to the right orto the left of the drawing.

In the hydraulic circuit of FIG. 4, F designates a filter, the devicessuch as 53 and 54 are non-return valves, 55 a pipe supplying make-uphydraulic fluid so as to compensate for the losses in hydraulic circuit(this make-up supply of fluid is for example achieved from gaugedoleopneumatic accumulators) and 56 designates a safety valve.

The devices such as 57 and 58 are devices for regulating the flow rateof the hydraulic fluid supplied to the jacks during gripping orreleasing movement of the jaws respectively.

The position shown in FIG. 4 of the assembly of the control slide-valves46 and 47 corresponds to the gripping position of the jaws of the twogripping devices 6 and 8, the winch 13 being stopped (arm 49 on contact0), which corresponds to the stopping of the mova ble upper grippingelement 8.

The elements 59, 60 and 61 having been brought, for example, into theposition corresponding to the operation of lowering the pipe, by movingto the right of FIG. 4 the assembly of the two distributing slide-valves46 and 47 (which is achieved by controlling the electrovalve 50 so as tomove its slide to the left) the jaws of the lower gripping device 6 aremoved away from each other, while the jaws of the upper gripping device8 remain in gripping position.

The arm 49 for electric contact comes unto the contact M, which soactuates the winch 13 as to raise the gripping device 8.

A not-illustrated device, such as an electric retarding device, may beused so that the actuation of winch 13 be effected only after openingthe jaws of the device 6.

By movingto the left of FIG. 4 the assembly of the distributingslide-valves 46 and 47 by electrically controlling the electrovalve 50displacing the slide of this electrovalve toward the left of thedrawing, the jaws of the upper gripping element 8 are moved away fromeach other, while those of the lower element 6 remain in their grippingposition.

By electrically controlling the electrovalve 50, it is thus possible toperform the different operations, the succession of which, following apredetermined order, enables the lowering or raising of the flexibledrill pipe after having selected the position of the elements 59, 60 and61.

This control may either be manual, by actuating an electrical switch(not shown) or made fully automatic by using a programming device whichmay be of any suitable known type, for example a drum driven in rotationat a constant speed and provided around its periphery with electricalcontacts having the shape of annular sectors which will successivelyactuate at predetermined instants which are functions of theirrespective positions on the drum, a switch located in the immediatevicinity of this drum and controlling the electrovalve 50. Thisprogramming may also be achieved by automatic control based on thedisplacements of the upper gripping device, for example by means ofphotoelectric cells placed at convenient levels, at the upper and lowerends of the stroke of this upper gripping device.

It has been assumed in the foregoing that the gripping action by each ofthe gripping devices 6 and 8 is performed by moving simultaneously thedifferent jaws of these devices into gripping position.

It will also be possible to so constitute the gripping means of the jawsthat the weight of the flexible line 1 which is supported by each of thegripping devices 6 and 8 alternatively (this weight varying moreover asa function of the unreeled length of the flexible pipe) is taken up bysuccessively moving into gripping position the different belts whichconstitute each .of these devices (dephased gripping), by first movinginto gripping position in each gripping element the element whosedisplacement, under the action of the load is the smallest, the elementsbeing moved out of gripping position by following the reverse order.

This will make it possible for the flexible pipe to expand below eachgripping element, under the action of the fraction of the weight W whichis supported by this element and by the elements which are already intheir gripping position, thereby reducing the relativedisplacementresulting from a sliding motion or creeping or from adeterioration of the wall of the flexible pipe within this element.

In practice, since the gripping action by each element becomes effectiveonly after some time from the instant of actuation of the jacks such as17a, 17b (automatic clamping action of the flexible pipe by the jaws 15and 16, FIG. 1), there will be some overlapping of the periods forsuccessively movinginto gripping position the elements of each device 6and 8, so as to not overload any gripping element.

Assuming for example that the overall load W is 200 tons and each of thedevices 6 and 8 includes four gripping elements, i.e.', the maximum loadwhich is to be supported by each element is 50 tons; the gripping of theflexible pipe 1 by the upper gripping element 8 in the lowermostposition of the latter may be achieved by first moving into grippingposition the jaws 21b and 22b (FIG. 4) of the upper element of thisgripping device and by'increasing through actuation of the winch theload supported by this element up to about 40 tons, after the automaticclamping action has been initiated while the lower gripping element 6 isat the same time progressively unloaded.

The jaws 23b, 24b of the nearest lower element are then moved intogripping position without waiting that the jaws 21b, 22b have reachedtheir maximum load of 50 tons.

Similarly, as soon as the fraction of the weight W supported by theassembly of the jaws 21b, 22b and 23b, 24b reaches about 50 40 90'tons,the jaws 25b, 26b are moved into gripping position etc.

This method of gripping, wherein an element is placed into its grippingposition without waiting that the previously actuated element hasreached its maximum load, results in an elongation of the pipe betweenthese two elements, with respect to its position at the beginning of thegripping action by the lower element,

' such an elongation occurring duringthe above-defined overlappingperiod (for example when the load of the upper element of the grippingdevice continues to increase from the value 40 tons, corresponding tothe beginning of the gripping action of the next element, up to itsmaximum value 50 tons).

The arrangement, according to the invention, of the gripping elementsinside each of the gripping devices 6 and 8, such as illustrated in FIG.3, permits a relative displacement of the elements, corresponding to theelongation of the flexible pipe between these elements in their grippingposition.

Various modifications may be made without departing from the scope ofthe invention.

For example, both gripping devices may be movable along the axis of thepipe over a stroke C, so that the displacement of one of the grippingdevices in its released position is effected during the displacement ofthe elastic column or pipe carried by the other gripping device.

It will also be possible, for example, to use three gripping devicesarranged in series, the intermediate gripping device being stationarywith respect to the drilling rig, while the upper lower gripping devicesare movable along the axis of the column or the flexible pipe.

We claim:

l. A surface apparatus for handling an elastic column, provided with atleast two devices for gripping the elastic column, including a lowergripping device and an upper gripping device, each of said grippingdevicesbeing associated with means for placing said devices into and outof gripping position, means for displacing at least one of said grippingdevices along the axis of the column, means for actuating saiddisplacing means, adapted to always keep at least one of said grippingdevices in its gripping position and to perform the displacement of saidgripping device successively in a first direction corresponding to thegripping position of this device and in the oppositedirectioncorresponding to the released position of said gripping device, each ofsaid gripping devices being constituted by a plurality of separategripping elements located in series and interconnected through elasticmeans.

2. An apparatus according to claim 1, wherein said elastic means isconstituted by spring means.

3. An apparatus according to claim 1, wherein said elastic means isconstituted by jack means connected to a source of compressible fluidunder pressure.

4. An apparatus according to claim 1, wherein said elastic means isconstituted by connecting means made of elastomer.

5. An apparatus according to claim 1, wherein each of said grippingelements includes a housing extended by a sleeve member adapted toreceive the housing of an adjacent gripping element so as to constitutetherewith a telescopic mounting and wherein said elastic connectingmeans is constituted by a sleeve of elastic material secured both to theinternal wall of said housing and to the external wall of said housinginserted in said sleeve member.

6. An apparatus according to claim 1, wherein said gripping elementincludes a housing provided with means for gripping the elastic column,said gripping means including at least two gripping jaws having agripping surface substantially parallel to the axis of the column, eachof said jaws being slidable along a guide path integral with saidhousing and inclined with respect to the column axis so as to downwardlycome closer to this axis, thereby being adapted to perform an automaticclamping action on the elastic column, when the latter is subjected to avertical downwardly directed tension, each of said jaws being actuatedby jack means articulated to said housing and to said jaw, said jackmeans being adapted to move the jaw closer to the axis of the elasticcolumn in its gripping position and to move the jaw away from this axisin its released position. 7 Y

7. An apparatus according to claim 6, wherein each of said jaws isprovided with at least one roller which can roll along said inclinedguide path.

8. An apparatus according to claim 5, wherein said gripping surface ofeach jaw is adapted to partly cover the external surface of said elasticcolumn, said gripping surface being coated with an elastomer lining.

9. An apparatus according to claim 6, wherein said jack means is adaptedto move said jaw away from the axis of the elastic column against theaction of an elastic device adapted to automatically move said jawtoward this axis in the absence of any action of said jack means on saidjaw.

10. A method for operating a device according to claim 1, wherein ineach gripping device is successively actuated a first of said elementsfor gripping the elastic column, said first element being the one forwhich the displacement relative to its initial position, as a result ofthe applied load, is the smallest, then is actuated the gripping elementadjacent to said first gripping element, when said first element issubstantially in its gripping position, and so on for the differentgrlppmg elements of said gripping device.

11. A method according to claim 10, wherein gripping of the elasticcolumn by said adjacent gripping element is performed before saidgripping element has fully reached its gripping position, when the loadsupported by said first gripping element has reached a predeterminedfraction of its final load in its position of full'gripping.

1. A surface apparatus for handling an elastic column, provided with atleast two devices for gripping the elastic column, including a lowergripping device and an upper gripping device, each of said grippingdevices being associated with means for placing said devices into andout of gripping position, means for displacing at least one of saidgripping devices along the axis of the column, means for actuating saiddisplacing means, adapted to always keep at least one of said grippingdevices in its gripping position and to perform the displacement of saidgripping device successively in a first direction corresponding to thegripping position of this device and in the opposite directioncorresponding to the released position of said gripping device, each ofsaid gripping devices being constituted by a plurality of separategripping elements located in series and interconnected through elasticmeans.
 2. An apparatus according to claim 1, wherein said elastic meansis constituted by spring means.
 3. An apparatus according to claim 1,wherein said elastic means is constituted by jack means connected to asource of compressible fluid under pressure.
 4. An apparatus accorDingto claim 1, wherein said elastic means is constituted by connectingmeans made of elastomer.
 5. An apparatus according to claim 1, whereineach of said gripping elements includes a housing extended by a sleevemember adapted to receive the housing of an adjacent gripping element soas to constitute therewith a telescopic mounting and wherein saidelastic connecting means is constituted by a sleeve of elastic materialsecured both to the internal wall of said housing and to the externalwall of said housing inserted in said sleeve member.
 6. An apparatusaccording to claim 1, wherein said gripping element includes a housingprovided with means for gripping the elastic column, said gripping meansincluding at least two gripping jaws having a gripping surfacesubstantially parallel to the axis of the column, each of said jawsbeing slidable along a guide path integral with said housing andinclined with respect to the column axis so as to downwardly come closerto this axis, thereby being adapted to perform an automatic clampingaction on the elastic column, when the latter is subjected to a verticaldownwardly directed tension, each of said jaws being actuated by jackmeans articulated to said housing and to said jaw, said jack means beingadapted to move the jaw closer to the axis of the elastic column in itsgripping position and to move the jaw away from this axis in itsreleased position.
 7. An apparatus according to claim 6, wherein each ofsaid jaws is provided with at least one roller which can roll along saidinclined guide path.
 8. An apparatus according to claim 5, wherein saidgripping surface of each jaw is adapted to partly cover the externalsurface of said elastic column, said gripping surface being coated withan elastomer lining.
 9. An apparatus according to claim 6, wherein saidjack means is adapted to move said jaw away from the axis of the elasticcolumn against the action of an elastic device adapted to automaticallymove said jaw toward this axis in the absence of any action of said jackmeans on said jaw.
 10. A method for operating a device according toclaim 1, wherein in each gripping device is successively actuated afirst of said elements for gripping the elastic column, said firstelement being the one for which the displacement relative to its initialposition, as a result of the applied load, is the smallest, then isactuated the gripping element adjacent to said first gripping element,when said first element is substantially in its gripping position, andso on for the different gripping elements of said gripping device.
 11. Amethod according to claim 10, wherein gripping of the elastic column bysaid adjacent gripping element is performed before said gripping elementhas fully reached its gripping position, when the load supported by saidfirst gripping element has reached a predetermined fraction of its finalload in its position of full gripping.